Iranian Supreme Leader Ali Khamenei used the occasion to post an English-subtitled video on his website questioning whether the Holocaust happened at all.

The three-minute video, entitled “Are the Dark Ages Over?,” features audio of a March 2014 speech in which the Iranian leader claimed, “No one in European countries dares to speak about the Holocaust, while it is not clear whether the core of this matter is reality or not. Even if it is reality, it is not clear how it happened.”

The video also showed images of prominent European Holocaust deniers, including the British historian David Irving.

Iran’s revolutionary regime has included some outspoken Holocaust deniers and revisionists, to the point at which scepticism or flat-out denial of the historic nature of the Holocaust has often appeared to be an official Iranian government position.

Current Iranian president Hassan Rouhani was notably evasive and equivocal in discussing the Holocaust during a 2013 CNN interview. And in 2006, current Iranian foreign minister Javad Zarif, who is considered one of the regime’s most influential moderates, refused to say whether he personally believed 6 million Jews had been murdered in the Holocaust when the question was directly posed to him during an event at Columbia University.

Earlier this month, most international and US sanctions on Iran were lifted as a result of the July 2015 nuclear deal, a development that paves the way for multi-billion-dollar trade deals and even a degree of diplomatic normalization between Iran and Western nations. Rouhani has visited both Italy and France this week.

Khamenei’s message, however, shows that the thaw has had little impact on some of the least-savoury aspects of the regime and its ideology.